the free lunch is economic growth. Economic growth makes his statement feasible without tax increases, and frankly also with or without private accounts. Obviously your counter-argument would be that my definition of greater benefits (which I define in real terms) is not correct.
The actuarial deficit posits and factors in economic growth. Yes, under the present system, if we tax ourselves to pay for it, and it does not slow economic growth, then yes, retirees will get more because benefits are tied to the growth in wages, not inflation. That has to go. Bush said otherwise, overall.